Flow rate meter

Abstract

A flow rate meter is proposed which serves to ascertain the quantity of a flowing medium, in particular the quantity of air aspirated via an air intake tube by an internal combustion engine. The flow rate meter includes a measuring body which is pivotable counter to a restoring force about a bearing shaft supported in the housing in accordance with the quantity of the medium flowing therethrough. The flow rate meter further includes a damping body which is likewise pivotable about the bearing shaft and defines a damping chamber in the form of a movable wall, with respect to the flow conduit. The measuring body and the damping body are coupled rigidly to one another by means of crosspieces. The invention comprehends embodiments wherein either the damping body or the measuring body is directly connected with a hub held in a rotationally fixed manner on the bearing shaft. The housing wall about the hub is provided such that a leakage gap formed between the housing wall and the hub terminates at one end outside the damping chamber downstream of the measuring body. As a result, the harmful effects on the measuring competence of the flow rate meter which would be caused by air flowing via the leakage gap are avoided; thus, even very small flowing air quantities such as occur at low engine rpm levels can still be measured accurately.

What is claimed and desired to be secured by Letters Patent of the United States is: 
     
       1. A flow rate meter having a housing, said housing having a flow conduit in which a measuring body is disposed, said measuring body pivotable about a bearing shaft mounted in said housing counter to a restoring force, said measuring body being arranged to pivot in accordance with a quantity of medium flowing therethrough, said flow rate meter further having a damping body pivotable about said bearing shaft so as to define a damping chamber with respect to said flow conduit, said flow rate meter being intended in particular for measuring a quantity of air aspirated via an air intake tube by an internal combustion engine, characterized in that said measuring body and said damping body are rigidly coupled to one another by means of at least one crosspiece, said measuring body and said damping body comprising flow rate elements, one of said flow rate elements being directly connected with a hub provided on said bearing shaft in a rotationally fixed manner, said housing further being provided with a wall extending arcuately about said hub, and said wall and said hub provide therebetween a leakage gap terminating at one end outside said damping chamber downstream of said measuring body. 
     
     
       2. A flow rate meter as defined by claim 1, further characterized in that said flow rate element directly connected with said hub is said measuring body, and said leakage gap extends from said housing upstream of the measuring body to downstream of said measuring body and exterior to said damping chamber. 
     
     
       3. A flow rate meter as defined by claim 2, further characterized in that said hub is provided with a nose, and said wall extends arcuately about said hub such that as said measuring body is deflected, said leakage gap progressively becomes wider. 
     
     
       4. A flow rate meter as defined by claim 3, further characterized in that said damping body is connected with said at least one crosspiece by means of releasable connecting elements. 
     
     
       5. A flow rate meter as defined by claim 1, further characterized in that said flow rate element connected directly with said hub is said damping body and the leakage gap extends from said damping chamber to downstream of the measuring body exteriorly of said damping chamber. 
     
     
       6. A flow rate meter as defined by claim 5, further characterized in that said measuring body is connected with said at least one crosspiece by means of releasable connecting elements. 
     
     
       7. A flow rate meter as defined by claim 6, further characterized in that said flow conduit includes lateral walls, at least one of which walls defines a lateral gap with said measuring body, and further wherein said lateral gap varies in width with deflection of said measuring body, and said lateral gap is narrow with low deflection and widens as said measuring body is deflected by higher than idling air flow rates. 
     
     
       8. A flow rate meter as defined by claim 7, further characterized in that said housing wall extending arcuately about said hub extends asymetrically about said hub, and said measuring body and said housing wall form therebetween a gap, whereby said gap becomes continuously larger with increasing deflection of said measuring body. 
     
     
       9. A flow rate as defined by claim 1, further characterized in that said measuring body and said damping body comprise butterfly valves.